/Engine/Source/Runtime/Engine/Classes/Engine/StreamableManager.h
Templated struct that provides type tags (no RTTI) for internal data used on StreamableHandle Type IDs are not stable across multiple processes, so should never be directly serialized or stored.
template<typename SubClassType> struct TStreamableHandleContextData : public [FStreamableHandleContextDataBase](API\Runtime\Engine\Engine\FStreamableHandleContextDataBase)